Evaluation of electrodeposited tungsten chemical modifier for direct determination of chromium in urine by ETAAS

摘要: The direct determination of chromium in urine by electrothermal atomic absorption spectrometry (ETAAS) using graphite tubes modified with tungsten is proposed. Modification the made electrodeposition over whole surface atomizer followed carbide formation heating tube inside its own furnace. For electrocoating, and a platinum electrode were connected to power supply as cathode anode, respectively, immersed solution containing 2 mg W 0.1% v/v HNO3. Then, 5 V was applied between electrodes during 20 min for atomizer. A SpectrAA 220 Varian spectrometer equipped deuterium background corrector used throughout. Undiluted (20 μl) delivered tungsten-treated chromium-integrated absorbance measured after applying suitable program maximum pyrolysis at 1300 °C atomization 2500 °C. With electrodeposited modifier, lifetime increased up four times when compared previous published methods Cr ETAAS, reaching 800 firings. Method detection limit (3 S.D.) 0.10 μg l−1, based on 10 integrated measurements sample low concentration. Two reference materials urines (SRM 2670) from National Institute Standards Technology (NIST) analyzed method validation. additional validation, results obtained eight human samples also Zeeman effect correction.